Julius Hallervorden was born the son of a hospital psychiatrist in Allenberg, East Prussia, in 1882. As of 1913, after studying medicine in Königsberg and undergoing further medical training, he worked in state institutions in Brandenburg, lastly as senior physician and head of the central pathology department. Besides his clinical work, Hallervorden successfully carried out neuropathological research. In 1922, he, together with neuroscientist Hugo Spatz, described the Hallervorden-Spatz syndrome.
As the head of the central pathology department of the state institutes in Brandenburg, Hallervorden assumed the management of the Histopathology Department of the Kaiser Wilhelm Institute for Brain Research in Berlin-Buch in 1938. Hallervorden had been informed of the murder of patients since the spring of 1940 at the latest. He had no scruples about using the brains of »euthanasia« victims for scientific purposes. In October 1940, he even carried out dissections in the Brandenburg killing centre himself. By the end of the war, he had obtained the brains of at least 700 murdered patients.
After 1945, Hallervorden worked at the Max Planck Institute for Brain Research in the Federal Republic until his retirement. He also continued to publish the results of his neuropathological research on »euthanasia« victims in scientific journals.